HYDROMETALLURGY
·
2022
·
IF 4.217
Jie Tang,Guihua Liu,Tiangui Qi,Qiusheng Zhou,Zhihong Peng,Xiaobin Li,Yilin Wang,Leiting Shen,Jiaping Zhao,HongJie Hao
An understanding of the mechanisms of reactive Al and AlN in a sodium aluminate solution contributes to the safe and effective utilization of secondary aluminum dross (SAD). This study demonstrates that the slurry temperature increased exponentially with an increase in the SAD dosage. Synergistic kinetic phenomena in the form of a large dosage and high temperature occurred initially in relatively stable microbubbles and later in the slurry. The leaching efficiencies of pure Al and AlN powders were greater than that of Al and AlN in SAD, respectively. Meanwhile, the leaching rate became higher for Al in SAD but lower for AlN in SAD compared to that of pure Al and AlN powder. The AlN particles in SAD were covered by Al(OH) 3 precipitated from the saturated solution in the bubbles. As a result, the relatively stable microbubbles with a thick border accelerated the reaction of Al and AlN and produced a saturated solution thereby changing the leaching efficiency and leaching rate of AlN in SAD. The embedded Al and AlN grains in the SAD, relatively stable microbubbles, and the SAD particles covered by Al(OH) 3 , synergistically changed the leaching mechanism. These results provide further understanding of the reaction mechanism of rich bubbles and facilitate the optimization of the comprehensive utilization of SAD.
研究领域:
冶金学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·Vol. 107
·期 11
·7352-7363
·
IF 3.5
Shengtai Zhang,Zhen Teng,Linzhen Wu,Yongqiang Tan,Chen Chen,Xiaosong Zhou
Designing waste forms using the cocktail effect of high-entropy ceramics can improve the efficiency of ceramic waste forms. In this work, traditional garnet (Y 1.2 Nd 1.8 Fe 5 O 12 , YIG) and high-entropy (HE) garnet (Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0 . 6 Fe 5 O 12 , HEG) are synthesized through ignition and plasma sintering to form dense ceramic waste forms. The chemical stability of YIG and HEG was studied by using static leaching tests at pH = 3, 5, 7, 9, 11. The results indicate that acidic environments can increase the leaching rate of ceramics. Leaching behavior leads to a decrease in lattice volume, but the elements remain uniformly distributed. The leaching mechanism indicates that YIG and HEG are controlled by dissolution and surface effect in the early stage (1–7 days) of leaching. The leaching mechanism in the later stage (14–42 days) is characterized by diffusion control. The diffusion coefficient of long-term leaching indicates that HEG is more suitable as the immobilization substrate for high-level radioactive waste (HLW) than YIG.
研究领域:
材料科学
·
核废物管理
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Kui Liu,Kuibao Zhang,Ting Deng,Jianjun Zeng,Baozhu Luo,Haibin Zhang
Gd 2 Zr 2 O 7 ceramic is considered as one of the most promising host minerals for the immobilization of high-level radioactive wastes . Here, the effects of grain size on the aqueous durability of Gd 2 Zr 2 O 7 ceramics were studied. Two kinds of leaching experiments were used to research Gd 2 Zr 2 O 7 ceramic powders and bulks with different grain sizes (5 nm, 78 nm, 1 μm and 18 μm). The results demonstrate that the normalized leaching rates decrease with the increase of grain size. Through characterization and analysis, it is concluded that the hydrolysis reactions of Gd 2 Zr 2 O 7 occur in the leaching experiment and the hydrolysates are Gd(OH) 3 and Zr(OH) 4 . Besides, all the samples after leaching exhibit slight lattice contraction, which decreases with the increase of crystal grain size. The influence of leaching on the elemental distribution is most significant for the sample with grain size of 5 nm. This study has theoretical guiding significance for the application of Gd 2 Zr 2 O 7 immobilization.
研究领域:
材料科学
·
核废料管理
·
环境化学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Limin Zhang,Yunyan Wang,Yong Ke,Zhumei Sun,Yun Li,Cong Peng,Mingfei Zhu,Yongjian Luo,Xiaobo Min
Zinc ferrite is a dominant phase in mass solid wastes generated from zinc or iron production, which causes the obstacle of metal recovery and recycling. A facile and efficient sulfuric acid leaching process of zinc ferrite assisted by copper powder was proposed in this study. The effects of factors on the leaching of zinc ferrite and copper were investigated. The results showed that zinc ferrite and copper were coupled and leached. The complete dissolution of zinc ferrite was obtained with wide ranges of leaching conditions. The shortest time for the complete dissolution of zinc ferrite was 10 min at 80 ℃ under the conditions: copper to zinc ferrite molar ratio of 1.5, sulfuric acid concentration of 100 g/L, liquid to solid ratio of 30 mL/g, and copper powder of + 38.5–20 μm. The least consumption of copper to realize the complete dissolution of zinc ferrite was 27.15%. The leaching kinetics was studied by the shrinking core model. It was found that zinc ferrite leaching assisted by copper was controlled by surface chemical reaction. The apparent activation energies for zinc, iron, and copper are 56 kJ/mol, 56 kJ/mol, and 50 kJ/mol, respectively. Characterization of the leaching residues and determination of iron and copper species in the leaching solution showed galvanic corrosion took place between zinc ferrite and copper, enhancing their acid dissolution.
研究领域:
冶金学
·
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Zhangyi Huang,Jiaochun Zheng,Yutong Zhang,Yang Shi,Junjing Duan,Ruichong Chen,Tiecheng Lu,Zhijun Wang,Jianqi Qi,Haomin Wang
Gd 2 Zr 2 O 7 (GZO)-based ceramic waste form has attracted broad interest due to its potential applications in the long-term disposal of high-level nuclear waste . However, its high-capacity isomorphic immobilization and leaching mechanism are not well understood yet. Herein, GZO-based waste form with a single pyrochlore phase and homogeneous element distribution, achieving an isomorphic waste load as high as 50 wt%, was fabricated successfully. Isomorphism failure of the waste form is due to the Ln 6 MoO 12 (Ln is lanthanides) formation and direct precipitation of PdO from the oversaturated solid solution. Chemical durability tests showed that the 42-day leaching rates of nearly all elements in the waste form with the maximum waste load were only between 10 −6 and 10 −5 gm −2 d −1 . The leaching of 0.5SW·0.5GZO over a period of 42 days is primarily controlled by dissolution, leading to a gradual restructuring of the surface in two distinct stages: the formation of an amorphous passivation film and the agglomeration of amorphous precipitates. Notably, the formation of the amorphous passivation film stands as the primary factor influencing the leaching rate of the waste form.
研究领域:
核废料管理
·
材料科学
·
放射性废物处理
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）